In some patients with multiple sclerosis, the suppressor T-cell response is elevated against measles virus. Non-specific suppressor cell activity is at normal levels in MS patients in stable phase of this disease. Suppressor cell response to myelin and axolemma antigens is depressed in some MS patients and most of these patients develop a positive cell-mediated immune response to these antigens. The T gamma subpopulation of lymphocytes was shown to interact with IgG antibody and kill measles virus infected cells in an antibody dependent lymphocyte cytotoxicity assay.